1. Field of the Invention
This invention relates to a method for culturing a microorganism, a method for synthesizing an organic compound utilizing a microorganism, a method for maintaining the microbial decomposing ability of a pollutant, a method for decomposing a pollutant utilizing a microorganism, and a method for remedying an environment utilizing a microorganism.
2. Related Background Art
In recent years, utilization of microorganisms in production of useful substances or in degradation of harmful substances has been actively studied, with the development of the applied microbial engineering.
At the beginning, the microbial technology was mainly applied to the synthesis of medicines and hormones which are difficult to be chemically synthesized and of high value added, or to the treatment of sewage or waste water of which amount to be treated makes physical or chemical treatment too expensive.
Now, various technologies including genetic engineering have been greatly developed, which enables production or decomposition of various substances and variegates the field of the microorganism utilization.
For example, in the field of the environment purification by means of microbial decomposition, attention has been attracted to the remediation of the environment polluted with organic chlorine compounds which are harmful to organisms and difficult to degrade.
For example, the soil in the manufacturing area of paper and pulp industry and semiconductor industry in as abroad is considered to be contaminated with chlorinated organic compounds such as tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE) and the like. Actually there have been many reports on detection of such chlorinated organic compounds through environmental surveys.
It is supposed that chlorinated organic compounds remaining in soil dissolves in groundwater via rainwater etc. thus spread over the area. There is a strong suspicion that these compounds are carcinogens, and further, these are quite stable in the environment; therefore contamination of groundwater, which is used as a source of drinking water, is a serious social problem.
The examples of strains capable of degrading TCE are given as follows:
Welchia alkenophila sero 5; ATCC 53570 (U.S. Pat. No. 4,877,736)
Welchia alkenophila sero 33; ATCC 53571 (U.S. Pat. No. 4,877,736)
Methylocystis sp. strain M (Agric. Biol. Chem., 53, 2903 (1989), Biosci. Biotech. Biochem., 56, 486 (1992), ibid. 56, 736 (1992)
Methylosinus trichosporium OB3b (Am. Chem. Soc. Natl. Meet. Dev. Environ. Microbiol., 55, 3155 (1989), Appl. Environ. Microbiol., 55, 3155 (1989), Appl. Biochem. Biotechnol., 28, 887 (1991), Japanese Laid-Open Patent Application No. (JP-A)-2-92,274, JP-A-3-392,970
Methylomonas sp. MM2 (Appl. Environ. Microbiol., 57, 236 (1991)
Alcaligenes denitrificans sp. xylosoxidans JE 75 (Arch. microbiol., 154, 410 (1990)
Alcaligenes eutrophus JMP 134 (Appl. Environ. Microbiol., 56, 1179 (1990)
Alicaligenes eutrophus FERM P-13761 (JP-A-7-123,976)
Pseudomonas aeruginosa J1104 (JP-A-7-236,895)
Mycobacterium vaccae JOB5; ATCC 29678 (J. Gen. Microbiol., 82, 163 (1974), Appl. Environ. Microbiol., 53, 2960 (1989)
Pseudombnas putida BH (Journal of Japan Sewage Work Association 24., 27 (1987)
Pseudomonas sp. G4; ATCC 53617 (Appl. Environ. Microbiol., 52, 383 (1986), ibid. 53, 9494 (1987), ibid. 54, 951 (1988), ibid. 56, 1279 (1990), ibid. 57, 1935 (1991), U.S. Pat. No. 4,925,802
Pseudomonas mendocina KR-1 (Bio/Technol., 7, 282 (1989))
Pseudomonas putida F1 (Appl. Environ. Microbiol., 54, 1703 (1988), ibid. 54, 2578 (1988))
Pseudomonas fluorescens PFL 12 (Appl. Environ. Microbiol., 54, 2578 (1988))
Pseudomonas putida KWI-9 (JP-A-6-70,753)
Pseudomonas cepacia KK 01 (JP-A-6-227,769)
Nitrosomonas europaea (Appl. Environ. Microbiol., 56, 1169 (1990))
Lactobacillus vaginalis sop. nov; ATCC 49540 (Int. J. syst. Bacteriol., 39, 368 (1989)
Nocardia corallina B-276; FERM BP-5124, ATCC 31338 (JP-A-8-70,881)
In the field of microbial production, the production of pharmacologically active substances and enzymes has been drawing attention.
In the above mentioned fields of microbiological technology, high cost is a common obstacle. To overcome this problem, for example, in the field of the microbial substance production, it has been proposed a method for economic operation of a reactor by operating the reactor measuring the cell concentration and redox potential in the reactor to introduce the optimal amount of substrate and air according to the predetermined optimal relationship between the cell mass, substrate concentration and aeration (JP-A-04-231,601 and JP-A-06-210,297). JP-A-06-062,831 teaches to design the shape of a reactor for efficient growth of the producing microorganism and recovery of cells and the synthesized product. Also in the field of the microbial degradation of organic compounds and environment remediation, various technologies have been developed to improve the degradation efficiency of the organic compound. JP-A-8-117,777, for example, discloses a method for improving the mixing efficiency of the microbe-holding carrier in a liquid-flow type biochemical reaction device.
The present inventors have made various studies to improve the efficiency in the microbial manufacturing, and in microbial decomposition of organic compounds, and found that the use of electrolyzed water is highly effective in improving the efficiency of the microbial proliferation, which is extremely advantageous for efficient microbial production of a substance, and in improving the efficiency of the microbial decomposition of organic compounds. Specifically, it has been found that when a microorganism is grown in a culture medium containing electrolytic water, the growth rate and the maximum cell density are both greater than those in an ordinary culture medium. It has been also found that when an organic compound is degraded by a microorganism in the presence of electrolytic water, the organic compound is decomposed in a shorter period of time than in a control medium.
The present invention has been made on the novel findings mentioned above. An object of this invention is to provide a method for cultivating a microorganism more efficiently.
Another object of this invention is to provide a method for producing an organic compound by using a microorganism more efficiently.
Another object of this invention is to provide a method for degrading a pollutant more efficiently by using a microorganism which is capable of decomposing the pollutant.
Another object of this invention is to provide a method for decomposing an organic compound more efficiently by the use of a microorganism.
Yet another object of this invention is to provide a more efficient method for remedying an environment utilizing microorganisms.
To accomplish the objects mentioned above, one embodiment of the present invention provides a method for culturing a microorganism which comprises a step of culturing the microorganism in a culture medium containing a carbon source being metabolizable by the microorganism and an electrolyzed water obtained by electrolysis of water in an electrolytic cell.
According to the other embodiment of the present invention, there provided is a method for culturing a microorganism comprising a step of culturing the microorganism in a culture medium containing a carbon source being metabolizable by the microorganism and an acidic water having a pH value of 1-4 and redox potential of 800 mV-1500 mV.
According to the other embodiment of the present invention, there provided is a method for culturing a microorganism comprising a step of culturing the microorganism in a culture medium containing a carbon source being metabolizable by the microorganism and an alkaline water having a pH value of 10-13 and a redox potential of xe2x88x921000 mV-800 mV determined by using a platinum electrode as a working electrode and a silver-silver chloride electrode as a reference electrode.
By means of the constitution of the present invention, the growth rate and the maximum cell density in the culture medium are increased.
To accomplish the objects mentioned above, one embodiment of the present invention provides a method for producing an organic compound using a microorganism which comprises a step of reacting a first compound with a microorganism capable of producing a second organic compound from the first organic compound in the presence of an electrolyzed water obtained by electrolysis of water in an electrolytic cell.
According to the other embodiment of the present invention, there provided is a method for producing an organic compound using a microorganism which comprises a step of reacting a first compound with a microorganism capable of producing a second organic compound from the first organic compound in the presence of an acidic water having a pH value of 1-4 and an oxidation-reduction potential of 800 mV-1500 mV.
According to the other embodiment of the present invention, there provided is a method for producing an organic compound using a microorganism which comprises a step of reacting a first compound with a microorganism capable of producing a second organic compound from the first organic compound in the presence of an alkaline water having a pH value of 10-13 and an oxidation-reduction potential of xe2x88x921000 mV-800 mV determined by using a platinum electrode as a working electrode and a silverxe2x80x94silver chloride electrode as a reference electrode.
To accomplish the objects mentioned above, one embodiment of the present invention provides a method, for producing an organic compound using a microorganism which comprises cultivating a microorganism capable of producing from a first organic compound a second organic compound in a culture medium containing a carbon source and an electrolyzed water obtained by electrolysis of water in an electrolytic cell; isolating the grown microorganism from the culture medium; and reacting the microorganism with the first compound to produce the second organic compound.
By means of the constitution described above, the productivity of the microbial production of a substance can be improved.
To accomplish the objects mentioned above, one embodiment of the present invention provides a method for maintaining an ability of a microorganism to decompose a pollutant which comprises a step of culturing a microorganism expressing a pollutant-decomposing activity in a culture medium containing an electrolyzed water obtained by electrolysis of water in an electrolytic cell.
To achieve the above objects, one embodiment of the present invention provides a method for degrading a pollutant which comprises a step of contacting a microorganism having a pollutant-decomposing ability with a pollutant in a presence of an electrolyzed water obtained by electrolysis of water in an electrolytic cell.
According to the other embodiment of the present invention, there provided is a method for degrading a pollutant which comprises a step of contacting a microorganism having a pollutant-decomposing ability with a pollutant in the presence of an acidic water having a pH value of 1-4 and a redox potential of 800 mV-1500 mV.
According to the other embodiment of the present invention, there provided is a method for degrading a pollutant which comprises a step of contacting a microorganism having a pollutant-decomposing ability with a pollutant in the presence of an alkaline water having a pH value of 10-13 and a redox potential of xe2x88x921000 mV-800 mV determined by using a platinum electrode as a working electrode and a silverxe2x80x94silver chloride electrode as a reference electrode.
To accomplish the objects mentioned above, one embodiment of the present invention provides a method for remedying an environment which comprises a step of decomposing a pollutant contained in the environment by contacting the pollutant with a microorganism capable of decomposing the pollutant in the presence of a water containing an electrolyzed water obtained by electrolysis of water in an electrolytic cell.
According to the other embodiment of the present invention, there provided is a method for remedying an environment which comprises a step of decomposing a pollutant contained in the environment by contacting the pollutant with a microorganism capable of decomposing the pollutant in the presence of an acidic water having a pH value of 1-4 and a redox potential of 800 mV-1500 mV.
According to the other embodiment of the invention, there provided is a method for remedying an environment which comprises a step of decomposing a pollutant contained in the environment by contacting the pollutant with a microorganism capable of decomposing the pollutant in the presence of an alkaline water having a pH value of 10-13 and a redox potential of xe2x88x921000 mV-800 mV determined by using a platinum electrode as a working electrode and a silverxe2x80x94silver chloride electrode as a reference electrode.
By means of the constitution described above, the efficiency of the decomposition of the pollutant and the purification of the environment is much improved.
Further, the advantage of the present invention is that the microorganism can function effectively even under conditions detrimental to the activity of the microorganism, e.g. the temperature as low as 4xc2x0 C. or a presence of an organic solvent in a concentration exceeding 1% in the culture medium which are generally harsh conditions for the viability and growth of microorganisms.